Effects of inoculation of cyanobacteria on nitrogen status and nutrition of rice (Oryza sativa L.) in an Entisol amended with chemical and organic sources of nitrogen

A field experiment was conducted with wetland rice (Oryza sativa cv. IR-36) in a sandy clay loam soil (Entisol) to study the effect of inoculation with a soil-based mixed culture of four diazotrophic cyanobacteria,Aulosira fertilissima, Nostoc muscorum, N. commune andAnabaena spp., on the N-flux in inorganic NH₄ ⁺+NO₃ ^?+ NO₂ ^?), easily oxidizable, hydrolysable and non-hydrolysable forms of N in soil during vegetative growth periods of the crop. Effects on grain and straw yield and N uptake by the crop were estimated. The effects of applying urea N and N as organic sources, viz.Sesbania aculeata, Neem (Azardirachta indica) cake and FYM, each at the rate of 40 kg N ha^?1, to the soil were also evaluated. Inoculation significantly increased the release of inorganic N, evidenced by its increased concentrations either in soil or in soil solution. However, such increases rarely exceeded even 4% of total N gained in different froms in the soil system by inoculation during the vegetative growth stages of the rice plant, when the nutritional requirement of the plants is at a maximum. Most of the N₂ fixed by cyanobacteria remained in the soil as the hydrolysable form (about 85%) during this period. Inoculation caused an insignificant increase in grain (8%) and straw (11%) yield, which was, however, accompanied by a significant increase in N uptake by the grain (30%) and an increase in total uptake of 15.3 kg N ha 1. Such beneficial effects of inoculation varied in magnitude with the application of organic sources, with farmyard manure (FYM) being the most effective. Application of urea N, on the other hand, markedly reduced such an effect.     

Bio-extraction of Potassium from Glauconite Nano-particle in an Alfisols of Southern India

ABSTRACT

Glauconite is a potassium (K) bearing mineral, which generally contains 6–10% K₂O and mostly available in various natural deposits in India. Glauconite mineral was converted to nano-particle form by grinding in a high-energy ball mill. The release of K from glauconite nano-particle in soil was studied in a pot culture experiment. Five different treatments viz., 0 mg K₂O kg^?1, 100 mg K₂O kg^?1, 150 mg K₂O kg^?1, 200 mg K₂O kg^?1 used glauconite nano-particle (GNP) as a K source and 100 mg K₂O kg^?1 from muriate of potash (MOP), were applied in soil to grow maize (Zea mays L.) plant. The highest K⁺ concentration was observed in shoot at the application of 200 mg K₂O kg^?1 through GNP and recorded 2 times more K⁺ concentration in shoots as compared to 0 mg K₂O kg^?1 treatment whereas 1.1 times more than the MOP treated soil at 5^th harvesting stage. Selected plant physiological parameters namely electrical conductivity of plant cell, height, leaf area and nitrate reductase activity were also recorded maximum at 200 mg K₂O kg^?1 GNP treated soil. Overall, glauconite nano-particle could supply K throughout the growth period and enhanced biomass yield of maize plant without showing any K deficiency symptom.     

Availability of residual fixed ammonium to crops

Summary To estimate the availability of residual fixed NH ₄ ⁺ -N to crops and its participation in the general nitrogen cycle, a field experiment without N fertilization was conducted with maize as the test crop planted at two densities. The experiments were carried out on the layout of a previous experiment, where the maize was cropped with identical densities but was fertilized with five different N treatments. Irrespective of planting density, the residual fixec NH ₄ ⁺ -N and KOBr-extractable N content in soil decreased with increase in the period of crop growth. N uptake by the plant was significantly higher in plot with the high- than the low-density planting. Availability of residual fixed NH ₄ ^– -N to the crop is discussed.     

Toxicokinetics, recovery, and metabolism of metamitron in goat

Toxicokinetic behavior and metabolism studies of metamitron and its effect on the cytochrome P(450) content of liver microsomal pellet were carried out in black Bengal goats after a single oral administration at 278 mg kg(-1) and consecutive oral administration of 30 mg kg(-1) for 7 days. Metamitron was detected in the blood sample at 0.08 h (12.0 +/- 0.87 microg mL(-1)), maximum at 4 h (84.3 +/- 8.60 microg mL(-1)) and minimum (14.6 +/- 1.67 microg mL(-1)) at 36 h blood sample after a single oral administration. The absorption rate constant was 0.69 +/- 0.09 h(-1). The Vd(area) (2.00 +/- 0.08 L kg(-1)) and t(1/2)beta (8.98 +/- 0.70 h) values suggested wide distribution and long persistence of the compound in the body. The values of T approximately B (0.80 +/- 0.04), F(c) (0.55 +/- 0.01), Cl(B) (0.15 +/- 0.00 L kg(-1) h(-1)), and K(21) (0.41 +/- 0.03 h(-1)) suggested that metamitron retained in the blood compared to that in the tissue. Maximum concentration of metamitron residue was found in the adrenal gland followed by bile on day 4 of single oral administration. The higher Cl(R) compared to Cl(H) value indicated the excretion of the major portion (34-40%) through urine compared to feces (20-26%). Maximum concentrations of metamitron and its metabolite, deaminometamitron, were excreted through urine and feces at 48 and 24 h samples, respectively. The recovery of metamitron including its metabolite in terms of parent compound varied from 69.3 to 80.1%, of which contribution of metabolite in terms of parent compound varied from 53.1 to 63.0%. Repeated oral administration of metamitron at 30 mg kg(-1) for 7 days caused induction of the cytochrome P(450) content of liver microsomal pellet of goat, suggesting oxidative deamination of metamitron.     

Identification of resistance gene analogs in cotton (Gossypium hirsutum L.)

Sequence analyses of numerous plant disease resistance genes have revealed the presence of conserved motifs common to this class of genes, namely a nucleotide binding site (NBS) and leucine rich repeat region. In this study, thirty-three resistance gene analogs (RGAs) were cloned and sequenced from cotton (Gossypium hirsutum L.) following PCR with degenerate primers designed from the conserved NBS motif of plant resistance (R) genes. Phylogenetic analysis of the predicted amino acid sequences grouped the RGAs into four distinct classes from which several subgroups were delineated based on nucleic acid sequences. Gene database searches with the consensus protein sequences of each of the four classes and respective subgroups of cotton RGAs revealed their conserved NBS domains and homology to RGAs and known resistance genes from a variety of plant genera. Given the complete lack of knowledge regarding molecular organization of R genes in cotton, the cloned RGAs described here may be useful as probes to map, characterize, and manipulate R genes of the cotton genome. This revised version was published online in July 2006 with corrections to the Cover Date.     

Development of interspecific somatic hybrid cell lines in cultivated jute and their early characterization using jute chloroplast RFLP marker

A strong sexual incompatibility barrier that exists between the two cultivated jute species, Corchorus capsularis and Corchorus olitorius, limits the scope for improvement through genetic introgression. Protoplast fusion was carried out to generate interspecific hybrid cell lines. Cotyledonary cell protoplasts of C. capsularis and anthocyaninpigmented hypocotyl protoplasts of C. olitorius were used in the fusion experiments, which appeared to be visually useful in the early selection of the fused products. A chloroplast DNA (cpDNA) marker was developed in jute, which showed species‐specific hybridization patterns with EcoRI‐digested total genomic DNA of C. capsularis and C. olitorius. This cpDNA marker was used in the characterization of the somatic hybrid cell lines at their early stages of growth. Evidence for the presence of both types of cpDNA in the hybrid cell lines was obtained when the total genomic DNA of 4‐ to 7‐month‐old hybrid cell lines was challenged with the chloroplast DNA marker through Southern analysis. It was shown that the early segregation of the parental chloroplasts did not occur in jute, although this is common in other plant species. The hybrid nature of the fused cell lines could also be identified through peroxidase isozyme analysis. Isozyme banding patterns were complex and varied among the hybrid cell lines.     

Transformation Strategy for Managing Coupled Socio-Ecological Systems: Case Studies from Bangladesh and the Philippines

This study demonstrates the potential of transformation strategy (an approach that emphasizes strengthening interdependence among social and ecological systems) to rehabilitate degraded land by examining two cases in Bangladesh and one in the Philippines. The study considers the benefits obtained from forests and forest-related activities in the form of income and energy sources as key parameters to link the social system (local people) with the ecological system (forest). Qualitative and quantitative analysis of data on land use and socio-economic changes indicates that the transformation strategy improved both the wellbeing of local people and forest cover. In the case of the Philippines, social and ecological linkages were found to be strong, with local people rehabilitating the degraded land while also obtaining a high proportion of their total income from the activity. For the two Bangladesh cases, however, the level of dependency on the forest for livelihood declined as local people used their income from the forest and forest-related activities for diversification to non-forest activities.     

<Emphasis Type="Italic">Mangifera sylvatica</Emphasis> Roxb. in the Forests of South-Eastern Bangladesh: A Potential Underutilised Tree for Small-Scale Forestry

Mangifera sylvatica Roxb. is an underutilized wild tree species valued for its fruit, timber and medicine. It was believed to be widely grown in sub-tropical forests of Bangladesh, but nowadays can be seen only sparsely. Even though it has multiple uses, only the indigenous people in hilly areas use the fruit of this species, for cooking and making pickles. This study was designed to (1) observe the population status of M. sylvatica in the forests of south-eastern Bangladesh, (2) evaluate domestication potentiality through seed germination and early growth of seedlings, and (3) assess its suitability for small-scale forestry. Through 16 field visits in eight forest beats, 66 individual trees were identified and their GPS (global positioning system) coordinates were recorded. A seed germination rate of 83 % at 6 weeks after direct sowing was attained. The early growth of seedlings with fertilizer treatments showed no remarkable difference with seedlings without fertilization. The seed germination rate and early growth of seedlings indicates that this species can be easily domesticated and be incorporated into small-scale plantation programs. In that it has multiple use values, this species warrants promotion in small-scale forestry programs for conservation and benefiting the villagers.     

Modeling spatiotemporal distribution of Dipterocarpus turbinatus Gaertn. F in Bangladesh under climate change scenarios

ABSTRACT

Climate change affects plant phenology, spatial distribution, and even extinction of vulnerable species. Dipterocarpus turbinatus, locally known as garjan, is a valuable but vulnerable native tree species of Bangladesh whose spatial distribution under future climate change scenarios is not fully understood. The aim of this study was to examine the effects of present and future climatic scenarios on spatiotemporal distribution of D. turbinatus. We used maximum entropy species distribution modeling to perform the present and future habitat suitability of garjan under different climate scenarios. The representative concentration pathways (RCP) 2.6 and 8.5 were considered for bioclimatic variables from the Global Climate Model – Hadley Global Environment Model 2 Atmosphere-Ocean. The predictive accuracy of the model was more than 97% in both the training and test data. The prediction results suggest that compared to present areas (7624 km²) under moderate habitat class it will be 2755 km² and 1239 km², respectively, in 2050 and 2070 under RCP2.6 scenario and decreases more rapidly under RCP8.5 scenario. Besides, the prediction also indicates that the habitat of the species will shift toward the high altitudinal south-eastern corner of the country whereas local extinction might occur in the north-eastern part during 2070.